In general, various substrates such as a ceramic substrate, a resin substrate, and the like are used for mounting electronic components, such as a semiconductor device and the like, thereon. Such substrates have an excellent insulation property, but have weak strength and are vulnerable to external impact, and are often damaged during an assembly process. In addition, it is difficult for the above substrates to be used as a substrate for mounting a highly heat-dissipating electronic component, such as a light emitting diode (LED) lamp, generating a large amount of heat. A conventional aluminum substrate has a structure in which aluminum plate and a copper plate are laminated with an adhesive and the adhesive acts as an insulator. At this time, if the employed adhesive is an epoxy-based adhesive, there is a problem that the adhesive is peeled off as a temperature of the aluminum substrate is increased, on the contrary, a ceramic-based adhesive is resistant to heat but is expensive. In terms of price, which is one of the most important factors of competitiveness of products, the aluminum substrate is not competitive because the copper plate is utilized.
In particular, a lamp unit, such as a headlight, a brake light, a turn signal lamp or the like for a vehicle, is manufactured to have a curvature in consideration of a vehicle design. In an illumination lamp mounted in the curved lamp unit, in order to be able to irradiate light only forward or backward, a support body supporting the substrate is formed into a stepped shape and an illumination member such as the LED lamp is mounted on the stepped mounting surface using a flexible substrate. Korean Patent Registration No. 1235701 discloses a flexible circuit board for an LED backlight and a method of manufacturing the same, and Korean Patent Laid-Open Publication No. 2011-0086541 discloses a method of manufacturing advertisement using a light source module composed of a soft film type printed circuit board and an LED lamp. In addition, in Korean Patent Registration No. 10275080, a circuit board for mounting an LED and a method of manufacturing the same are disclosed, and Korean Patent Laid-open Publication No. 10-2009-0054898 discloses a method of joining and installing a lamp structure, which has an LED lamp to be mounted on a flexible printed circuit board (F-PCB) as one example of the above-described lamp unit, on a stepped-formed base plate.
The conventional flexible circuit boards disclosed above have problems in which it is difficult to maintain the shape of each circuit board in which a circuit pattern layer is formed on a flexible resin layer, and when an LED module is mounted on the flexible circuit board, a heat dissipation property cannot be improved.